This application is based on Patent Application No. 226,170/1998 filed on Aug. 10, 1998 in Japan, the content of which is incorporated hereinto by reference.
The present invention relates to an image generating apparatus and an image generating method, and more particularly to an apparatus and a method thereof for generating a graphic image that includes a frame buffer having a drawing port and a display port for a display device or like.
In the prior art, a frame buffer comprising both of a drawing port and a display port as shown in FIG. 2 has been provided as the frame buffer for generating a graphic image or for composing a graphic image, which is used in a computer graphics apparatus, such as a three-dimensional (3-D) game machine, 3-D simulator and the like.
In FIG. 2, reference numeral 110 designates a graphics drawing circuit, and 120 designates a frame buffer. A parameters showing translucency etc. is usually stored in a texture memory (not shown) in the graphics drawing circuit 110. The frame buffer 120 has a drawing port 121 and a display port 122 for a display device, and comprises a drawing area 123 for drawing, a display area 124 for display, and a base picture area 125 in which a base picture, text mapping, and the like are stored. A video signal read out from the display area 124 through the display port 122, is sent through a digital-to-analog (D/A) converter circuit 131 and a video output circuit 130 to a display device 140 for display.
In the conventional frame buffer as described above, a graphic image is written into the graphics drawing area through the drawing port 121, and a background image and base picture are referred to (read out) through the drawing port when a translucent graphic image is drawn. The display port 122 is a read-only output port through which an image is outputted to synchronize with a display on the screen. Therefore, the display port is not be utilized during the blanking period. Specifically, since the data is outputted actually during every screen (frame) period as shown in FIG. 3 that illustrates an operation of the display port, the display port 122 remains unutilized for 20% to 30% of the total of all screen periods.
Particularly, since the time period for generating an image per one screen is limited to a certain amount of the time when any two-dimensional (2-D) graphic image is to be generated. Thus, when the high-level graphics processing such as the translucent image processing occurs, it becomes more difficult to improve picture quality.
An object of the present invention is to provide an apparatus for and method of generating a graphic image which improves the access to any background or base picture data when it is referenced, by making an effective use of the display port during the blanking period of a vide signal, allows the drawing port to be used as a write-only port, thereby reducing any overhead that might occur when switching between reading and writing occurs and increases the speed of writing, and provides the higher image quality even when any high-level image generation such as the translucent graphics generation occurs for the 2-D graphics generation that occurs in realtime.
According to the present invention, the image generating apparatus may comprise a frame buffer having a drawing port and a display port for display device, and an address generating means for generating a read address for reading out reference data from the frame buffer during a blanking period of a video signal which is read from the frame buffer, wherein the reference data that has been read from the frame buffer by using the read address is outputted from through the display port during the blanking period.
According to the present invention, the apparatus may further comprise signal separating means for separating in response to a video synchronizing signal the data for reference data outputted from the display port and the video signal, and for transferring the reference data to graphics drawing means and the video signal to video output means.
According to the present invention, the frame buffer may be a dual buffer configured to include a drawing area for creating a graphic image and a display area for providing for displaying the created graphic image, and wherein the reference data includes drawing data that is currently being written into the drawing area.
According to the present invention, the frame buffer may include a base picture area in which a base picture and the like may previously be stored, the base picture providing a basis for creating a graphic image to be drawn and wherein the reference data may include such base picture or the like that may be read from the base picture area.
According to the present invention, the reference data may be data that is used for processing in drawing a translucent image.
According to the present invention, the drawing port may be used as a write-only port.
According to the present invention, an image generating method of an image generating apparatus including a frame buffer having a drawing port and a display port is provided, which may comprise the steps of generating a read address for reading reference data from the frame buffer during a blanking period of a video signal when the video signal is read from the frame buffer, and outputting the reference data read out from the frame buffer by using the read address, through the display port during the above blanking period.
According to the present invention, the display port, which was not utilized during the blanking period according to the prior art, may now be used as a read-only port so that it can be utilized efficiently for reading out the reference data. This allows for more references or accesses to the background, base pictures and like in the frame buffer. The graphic drawing port may be used as the write-only port. As those ports are dedicated as the read-only port or the read-only port, respectively, any overhead that might occur if each of the ports is switched between reading and writing may be reduced or eliminated, and the speed of reading and writing through the ports, respectively, may be increased accordingly. In particular, when any 2-D graphic image is to be generated in real-time, it is advantageously possible to provide a higher image quality when any high-level image generation such as the translucent graphics generation occurs.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.